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the analytical study of the diversity and relationships of organisms and species
a group of organisms wdefined as a common ancestor and all of its descendants; a monophyletic group
containing no common ancestor
a species or clade that is related to the ingroup, but less closely than any of the ingroup taxa are to each other
subject of systematics concerned with the naming of groups defined by their relationships and similarities
the species or clade that is being studied or of interest
stretch of a phylogenetic tree that represents the evolution of a lineage between nodes; the length of the branch can be indivative of the genetic or temporal distance between the nodes
a phylogenetic hypothesis produced from a cladistic analysis
Charles Lyell (1797-1875)
  • leading geologist of Darwin's time
  • formed the theory of uniformitarianism: there are no random catastrophes that we don't observe. Gradualism must be true!
  • Principles of Geology (1833) - the same geologic forces are working today as were working in the past, and at the same rates
  • Earth is OLD! Again!
a divergence in two branches of a cladogram or other phylogenetic tree that represents a last common ancestor
Theory of Natural Selection
  • variation in natural populations is widespread
  • most variation is heritable
  • more young are born/conceived every generation than can survive to reproduce (there is struggle for survival)
  • those that "win" this struggle do so based, at least in part, on their inherited characters
  • Therefore: the unequal ability of individuals to survive and reproduce must lead to the increased accumulation of certain traits over generations, or change in the population.
William Paley (1743-1805)
  • Natural Theology: Evidences of the Existence and Attributes of the Deity from the Appearances of Nature
  • we can understand God by looking at the adaptations of the organisms he has created
  • concluded God is both skillful and benevolent
an unresolved node of a cladogram or phylogenetic tree representing a radiation at which the sequence of branch splitting (bifurcation0 events is not or cannot be known
containing only a common ancestor and all of its descendants
the evolutionary history of a species or related group of species or organisms
shared by the taxon or clade of interest but not by its close relatives (outgroups)
containing only a common ancestor and some, but not all, of its descendants
a primitive character state
shared by the taxon or clade of interest as well as some of its close relatives (outgroups)
Hardy-Weinberg Equation assumptions
  • mating must be random
  • must have a large population size (infinite really)
  • no migration/emigration (exchange of alleles between populations)
  • no new mutation
  • no selection is acting
a method by which systematists attempt to determine clades by looking at the shared, derived character states in different taxa
terminal taxon
taxon being studied in a cladistic analysis that therefore ends up at the tips of the branches of a cladogram
a derived character state
Aristotle (384-382 BC)
  • Scala Naturae
  • "Great Chain of Being"
  • all beings, living and inanimate, occupy a ladder which, of course, culminates with humans
  • nothing changes
Charles Darwin (1809-1882)
  • University of edinburgh - "attempts" med school for two years and quit
  • Christ's College, U Cambridge - meets Henslow and Sedgwick
  • Henslow hooks Darwin up with Capt. Robert FitzRoy (Beagle)
a shared, derived character state
Georges Cuvier (1769-1832)
  • pretty much the first paleontologist
  • advocate of "catastrophism"--the idea that Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope.
  • species can go extinct. Believed┬áthat primarily catastrophes are what caused extinctions. Represents a slight movement away from religion/creation and toward true geology.
a character state that exists in two or more separate organisms because it was present in their last common ancestor
James Hutton (1726-1797)
  • Scottish geologist
  • promoted "gradualism" over catastrophism
  • Earth is OLD--not just 6,000 years old
Carolus Linnaeus (1707-1778)
  • father of taxonomy
  • Systema Naturae (1735-1770)
  • hierarchical, nesting classification system based on similarity of form
  • binomial naming system: genus + species
a named unit of life
Captain Robert FitzRoy (1805-1865)
  • captain of Beagle
  • meteorologist - advanced forecasting technology
  • hydrographer and surveyor
a shared, primitive character state
types of isolation
  • habitat isolation (terrestrial vs. aquatic habitats)
  • temporal isolation (winter vs. summer mating seasons)
  • behavioral isolation (mating rituals, bird calls)
  • mechanical or gametic isolation (incompatible reproductive organs or sex cells)
  • reduced hybrid viability (salamander)
  • reduced hybrid fertility (mule)
  • anagenesis
  • cladogenesis
  • allopatric speciation (two populations of the same species become separated and due to their new environments, evolve into different species. vicariance: the separation of a group by a geographical barrier (Pangaea breaking, Grand Canyon), causing a diversity of varieties and species to result)
  • sympatric speciation (new species evolve from a single ancestral species while inhabiting the same geographic region)
  • autopolyploidy (incorrect number of chromosomes)
  • adaptive radiation (rapid speciation of many diverse new forms in a geologically short period of time)
Erasmus Darwin (1731-1802)
  • amateur evolutionist
  • wealthy physician
  • Charles Darwin's grandfather
Jean-Baptiste de Lamarck (1744-1829)
  • compared fossil organisms with living relatives and concluded that species change over time
  • proposed first comprehensive theory of evolution
  • Philosophie Zoologique (1809-Darwin's birth year): made clear argument for evolution of species and proposed a mechanism based on two principles: 1) use vs. disuse, and 2) inheritence of acquired characters (basically wrong, but not completely)
John Gould (1804-1881)
  • Darwin's "bird man"
  • examined the many birds from the different Galapagos
  • found that they were mostly finches, seemingly variations of the common ground finch
Adam Smith (1723-1790)
  • "Invisible Hand"
  • Economic patterns are the result of many individuals struggling against one another for resources
  • No "designer" necessary
Thomas Malthus (1766-1834)
  • studied population growth in humans
  • overpopulation causes famine, plague, etc.
  • "Essay on Principles of Population" 1798
  • population, if unchecked, grows exponentially
  • resources tend to increase linearly
  • constant struggle for resources
Alfred Russell Wallace (1823-1913)
  • Outlined evolution by natural selection in a manuscript in 1808, sent to Darwin
biological species concept
  • a population or group of populations whose members have the potential to interbreed in nature and produce viable offspring BUT are unable to do so with other species
  • + applicable to many organisms
  • - cannot be used in fossil record
  • - need mating info
On the Origin of Species (1859)
  • lays out the mechanism of natural selection
  • does not use the word "evolution" until the end
Kimura''s Neutral Theory

  • the vast majority of mutations that arise are selectively neutral

  • the time it takes for a neutral mutation to become fixed in a population by genetic drift is independent of population size

  • nonsynonymous substitutions are already a subset of possible harmful substitutions, harmful nonsynonymous a subset of that, and advantageous synonymous even more unlikely

Richard Owen (1804-1892)
  • harsh critic of Darwin
  • talented anatomist and naturalist (named several of Darwin's finds)
  • believed species were created anew by God, but not all at once (recognized patterns in fossil record as real)
  • Thomas Huxley (1825-1895): Darwin's Bulldog. Fought almost too vehemently for Darwin's ideas.
  • Ernst Haeckel (1834-1919): German zoologist, spread Darwin's ideas in Germany
ecological species concept
  • different species fill different ecological niches (fishing cat vs. leopard cat)
What is a species?

  • basic category of biological classification
  • should be describing something real in nature
  • numerous species concepts exist
1. barrier is established
2. two populations diverge but still may be reproductively compatible
3. populations become reproductively incompativle, diverge more, become separate species
morphological species concept
  • if they look alike, same species
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